Guild Wars 2 dev blog explains WvW matchup system changes

There's been a small (but not insignificant) change to the way Guild Wars 2 determines world-vs.-world matchups. The official dev blog on the matter explains that, in the beginning, WvW matchups were chosen "by sorting all worlds in order of their Glicko rating, then counting off sets of three." As a result, matchups were often between the same three worlds, so ArenaNet introduced matchup variance to counter that problem.

However, it appears that the devs have made an adjustment to the matchup variance formula that causes the range of worlds with which a given server can be matched to be "greatly reduced." The idea behind the new formula is that "There will be fewer matches where one or two worlds are potentially steamrolled, though it comes at the cost of seeing more of the same worlds." That's all that the average GW2 player needs to know, but if you're interested in the math and statistics behind the change, check out the full post at the game's official site.